Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 438 PM EDT Tue Oct 17 2017 Valid 00Z Wed Oct 18 2017 - 00Z Fri Oct 20 2017 ...Heavy rain possible over parts of the Pacific Northwest... ...Heavy rain possible over the central-northeastern Florida Coast... A front extending from the Northern Rockies southwestward into the Pacific Northwest will move eastward to the Great Lakes/Middle Mississippi Valley into the Central Plains by Thursday. Moisture will be lacking with the boundary so there will be a dry frontal passage along the length of the front from the Northern High Plains to the Great Lakes/Central Plains through Thursday. In the meantime behind the front, onshore flow will stream moisture into the Pacific Northwest on strong low-level wind through Thursday morning when the strong low-level wind decreases. The flow will aid in producing rain over parts of the Pacific Northwest into parts of the Northern Rockies, ending overnight Tuesday when upper-level ridging moves over the Pacific Northwest/Northern Rockies. Meanwhile, a stronger front over the Eastern Pacific moves close to the Northwest Coast by Thursday morning. A deep upper-level trough associated with the boundary will begin to move over the Pacific Northwest on Wednesday afternoon and becoming stronger as the front approaches. The approaching upper-level trough and onshore flow will aid in producing rain over parts of the Northwest Coast on Wednesday. The rain will become heavy by Wednesday evening over the Northwest as the rain moves farther inland into the Northern Intermountain Region by Wednesday evening. Overnight Wednesday, the heavy rain will move southward along the Pacific Northwest Coast approaching Northern California by Thursday. Additionally, the snow levels will lower over the region with snow developing over the higher elevations of the Northern Cascades overnight Wednesday into Thursday morning. A persistent front over Southern Florida will remain quasi-stationary through Thursday. In addition, upper-level energy over Northeastern Florida will slowly move eastward out over the Atlantic by late Wednesday night while tropical moisture over Southern Florida slowly retreats southward south of the Florida Keys by Thursday. Showers and thunderstorms will develop over Southern Florida into Northeast Florida that will begin to wane early Thursday morning over the northeast coast. Showers and thunderstorms will continue over the southern tip of Florida through Thursday morning. Furthermore, moisture from the Pacific will move inland over Southern California into the Southwest as upper-level energy moves from the Pacific to the Southwest by Thursday. Light rain will begin over the Southwest overnight Wednesday into Thursday. The light rain will expand into parts of the Southern Rockies by Thursday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php